@SJohnRoss So after binging Toast of the Town (which is an absolute joy, by the way, can't wait to drag some people into playing it!) I have some comments and questions to make sure I understand your approach correctly :)
First off, I would call these sorts of adventure modules "sandboxes", where the focus is on giving the GM a very detailed and rich setup and then sort of leaving the actual resulting storyline for the GM and players to create during the game.
In general, I find these sorts of modules to be "the best" simply because... players will go and do unhinged things whether you want them to or not, so I find that adventure modules that try to be too rigid quickly end up in a spot where they become irrelevant to the actual sessions.
This might come from me being a very story-based and improv-heavy GM, so I'm probably highly biased in this assessment.
Secondly, I do believe this sort of approach is not really that uncommon nowadays! Although most games exist on a spectrum between "linear" and "sandbox" I just recently was going over the Pathfinder 2e Strength of Thousands module for a future campaign and was really getting excited about how sandboxy some parts of it got.
Do you agree with this comparison between High Trust games and sandboxes? Or are there additional nuances I'm missing?
Also, I do agree that a lot of the most prominent modules tend to fall more towards the linear side, by I think there are some gems in modern RPGs that would be to your liking as well!
So basically I think there is a market for these games, it's mostly suffered a change of "branding" in my opinion :)
In any case, that was highly enjoyable and I will definitely post about it as soon as I get some people together to run Toast of the Town, highly recommend it to any GMs that like more freeform modules!